The present invention relates to a device for adjusting the height of a plurality of tool carriers connected to a top panel of a bending press.
In general, bending presses are used for forming sheet materials, and for this purpose they comprise a top panel and a bottom panel disposed in a common vertical plane. One of the two panels is fixed, being supported at its ends, while the other panel is movable and is moved in the vertical plane by drive members which are generally situated at its two ends. Depending on the type of bending press, the moving panel can be constituted either by the top panel or by the bottom panel.
For forming purposes, one or more tools are fixed on the top panel by means of tool carriers, in register with one or more V-shaped matrices which are fixed to the edge of the bottom panel.
Each tool carrier comprises a tool spacer disposed vertically in register with the top panel, said tool spacer co-operating with a locking clamp which applies sufficient pressure to the tool or punch to position it in locked manner on the tool spacer.
When forming sheet material using such bending presses, one of the problems encountered is that of ensuring that the various tools and the matrix or matrices are parallel, and more generally that of ensuring that the facing edges of the two panels are parallel.
During forming, i.e. under the action of bending forces, the longitudinal deformation curves of the top and bottom panels, each in the form of a single arc, are substantially symmetrical about the separation plane between the panels. Thus, the maximum spacing between the panels is situated in the vicinity of their center and represents twice the maximum deformation of each panel.
It will thus be understood that since the tools are fixed on tool carriers connected to the top panel, the tools will take up positions such that the notional curve passing via the respective leading edges of the tools will have the same appearance as the longitudinal deformation curve of the top panel.
Thus, since the notional curve for the tools is further away from the matrix in its middle than at its ends, the folding of sheet material is more open in the center than at the ends.
It will thus be understood that maintaining parallelism between the various tools and the matrix or matrices of the bottom panel is a parameter which is essential for the precision and the quality of the bending performed.
A known solution for solving this problem consists in providing a device for adjusting the height of the tool carriers of the top panel so as to modify the vertical distance between the square of the top panel and the leading edges of the various tools.
The xe2x80x9csquarexe2x80x9d of the top panel is that portion of the panel or more exactly of the bottom face of the top panel which is placed facing the matrix of the bottom panel.
In conventional manner, the adjustment device comprises for each tool carrier, an adjustment wedge having a horizontal top face against which the square of the top panel is to bear while the bending press is working, i.e. during forming, and a sloping bottom face that bears against the top face of the tool spacer associated with said wedge.
The various wedges can slide independently of one another in the longitudinal direction of the top panel so as to adjust the vertical distance between each tool spacer and the square of the top panel, and thus above all the vertical distance between the leading edges of the tools and the square of the top panel.
That solution also makes it possible to compensate for deformation of the top panel during forming by adjusting the pre-curvature of the tool line, i.e. the line passing through the respective leading edges of the tools. This pre-curvature is in the form of a single arc parallel to that of the bottom panel.
Depending on circumstances, that solution also makes it possible to compensate for defects in the machining of the tools or in the machining of the top and bottom panels.
Nevertheless, in order for that solution to be satisfactory, it is essential for the length of the adjustment wedge to be greater than the length of the tool spacer with which it is associated so as to ensure that the bearing surface area between the horizontal top face of each adjustment wedge and the square of the top panel is sufficient to avoid local deformation of the top panel.
Furthermore, it is essential for the bearing surface area between each wedge and the square of the top panel to be conserved when the wedge moves relative to the tool spacer associated therewith while adjusting the height of the tool.
Thus, since the length of each wedge is necessarily longer than that of the tool spacer with which it is associated, the tool carriers serving to fix one or more tools have, until now, been spaced apart relative to one another. This spacing between two adjacent tool carriers corresponds substantially to the lengths of the end portions of two wedges projecting laterally beyond the top faces of the tool spacers.
Under such circumstances, and depending on the forming to be implemented, known adjustment wedges do not enable the tool carriers to be positioned, or more precisely do not enable the tool spacers to be positioned so that they touch one another while maintaining a sufficient bearing surface area between each wedge and the square of the panel.
It can be necessary, for example, for two tool spacers to be positioned so as to touch when the tool or fractioned tools need to be placed over a determined length equal to the sum of the lengths of the spacers so as to allow clearance for the side folds of sheet materials at the longitudinal ends of the lateral tool spacers.
Thus, it will be understood that with presently known adjustment wedges, if it is desired to place at least two tool spacers so that they touch each other, then the ends of the wedges associated with the tool spacers will necessarily come into contact with one another before the tool spacers themselves do.
Under such circumstances, it is not possible to make the spacers touch one another without moving at least one of the wedges and that would have the effect of modifying and thus spoiling the vertical adjustment of the spacer associated therewith.
An object of the present invention is to overcome the above-mentioned technical problems in satisfactory manner.
According to the invention, this object is achieved by means of a device for adjusting the height of a plurality of tool carriers connected to a top panel of a bending press, each tool carrier comprising a tool spacer disposed vertically in register with the top panel, the adjustment device comprising, for each tool carrier, an adjustment wedge which has a horizontal top face against which the square of the top panel is to bear while the bending press is in operation, and a sloping bottom face bearing against the top face of the tool spacer associated with said wedge, each wedge being of length greater than the length of the tool spacer associated therewith and being capable of sliding in the longitudinal direction of the folding press in order to adjust the height between each tool spacer and the top panel; wherein the ends of each wedge have engagement means to enable a wedge associated with a tool spacer firstly to overlap at least part of the top face of an adjacent tool spacer, and secondly to engage reversibly with the wedge associated with said adjacent tool spacer so that the two adjacent tool spacers touch one another, and wherein the square of the top panel can bear against the engagement means.
According to an advantageous further characteristic of the invention, the tool spacers are disposed in such a manner that their top faces have slope angles oriented in the same direction and the end portion of the top face of each tool spacer that is the closer to the top panel, is provided with a notch to enable the engagement means at one of the ends of the wedge associated with the adjacent tool spacer to come into contact with said notch.
According to yet another characteristic of the invention, the engagement means comprise a projecting element at one of the ends of each wedge, and, at the other end of each wedge, at least one end portion defining a recess of complementary shape, the projecting element of a wedge being designed to engage in the recess of complementary shape of the adjacent wedge.
According to yet another advantageous characteristic of the invention, the engagement means at the end of a wedge and the corresponding wedge are made as a single piece.
Thus, the device of the invention makes it possible to place at least two tool spacers so that they are touching while conserving sufficient bearing surface area between each adjustment wedge and the square of the top panel, and to do so independently firstly of the position of a wedge relative to the tool spacer which is associated therewith, and secondly of the positions of the wedges relative to one another.